Many heat exchange devices include tube sections with ends which must be closed or capped. For example, in the production of a heat exchange coil, certain end component tube sections must be completely closed to properly control the flow of fluid in and through the heat exchange coil.
In the past, several techniques have been used to completely close the end of a tube section. One method has been to solder a cap or end piece over the end of the tube to completely close the tube. Other methods have involved mounting the tube in a stationary chuck and closing the end thereof by forcing a rotating swagging tool into frictional engagement with the end portion of the tube. In this operation, heat is generated by the frictional engagement between the tool and the stationary tube section and the end portion of the pipe is conformed to a closed configuration.
Other apparatus used to close the end of a tube section include fixedly mounting the tube section and engaging the end by a rotating disc to pinch off and close the end of the tube section. An example of this type of apparatus is disclosed in the patent to D. Bowman, U.S. Pat. No. 3,225,998, issued Dec. 28, 1965. As in most prior art tube closing devices, the apparatus disclosed in the Bowman patent applies heat to the end of the tube prior to performing the closing process.
Other pipe closing apparatus operate by rotating the tube section about its longitudinal axis while engaging the end of the tube or pipe at spaced circumferential points thereabout to force the edge of the pipe inwardly either to form it or to close the pipe end. Examples of these devices are disclosed in the patents to R. K. Hopkins, U.S. Pat. No. 1,751,085, issued Mar. 18, 1930, the patent to Groppini, U.S. Pat. No. 3,793,863, issued Feb. 26, 1974 and the patent to W. L. Enghauser, U.S. Pat. No. 2,709,381, issued May 31, 1955. As in the patent to Bowman referred to above, each of these devices requires and uses the application of heat to the end of the pipe prior to the end forming operation.
While these prior art devices have been of limited success, these prior art systems have been overly complex and those requiring or generating heat during the forming operation introduce a critical disadvantage to the operation.